6 minute read
Super charging the view from above
t’s important work. By providing nutrients and shelter for animals and absorbing carbon emissions, seaweed plays a major role in sustaining marine ecosystems and in bu ering our warming climate. We all need to know whether our seaweed is doing OK. This survey is being conducted for the Department of Conservation (DOC). DOC will use the information in a report card on the state of our marine reserves – helping to chart the health of these vital seaweed forests over time. Where once researchers like Tait could only observe from above using expensive aircraft or satellites, drones now enable scientists to transform the scope and scale of their work. The small, remote-controlled units are easily deployed and can quickly survey large, hard-to-access areas. Plus, repeated flights can help illuminate changes over time that might otherwise go unnoticed. The drones also carry increasingly specialised camera equipment and sensors. But, perhaps more significantly, computing advances now mean the data this equipment captures can be enhanced using advanced processing power and artificial intelligence software. That package of drones and digital science is now opening up a whole new array of research opportunities.
Drone pilot Hamish Sutton (left) and Dr Leigh Tait check settings before launching another pre-programmed flight across the Taputeranga Marine Reserve. (Rebekah Parsons-King)
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hristchurch-based Sutton has been flying drones at NIWA for three years. He’s one of many drone pilots across the organisation who have passed advanced flight training courses approved by the Civil Aviation Authority. The main goal when operating these expensive flying machines, he says, is “don’t crash”. It’s a lesson that has come from hard experience – and even harder landings. Late last year, Sutton took the controls for a research project in the Canterbury high country. At Lake Tennyson, north of Hanmer Springs, boulders studded into moraines (material left behind by moving glaciers) are giving NIWA principal scientist Dr Andrew Lorrey and colleagues from Victoria University of Wellington and the University of Maine, vital clues about the glaciers that dominated the landscape tens of thousands of years ago. The fluctuation of glaciers and ice sheets – past and present – reflects their sensitivity to climate. Thanks to topographic data gleaned from the whirring drone, 4D glacier models put together by Lorrey and colleagues are revealing what the temperature changes were like when much larger glaciers underwent a rapid retreat. With much of the terrain covered in dense tussock, it’s been tricky up until now to define the moraines and know where the best Lake Tennyson boulder samples can be found. Enter drone-mounted LiDAR technology, which Lorrey likens to “x-ray vision”. LiDAR is a remote sensing method that can generate ultra-precise, 3D elevation maps of ground features. “It’s not terribly clear, in some cases, what’s going on in a landscape like this because vegetation gets in the way and the landforms we’re looking for are very subtle,” says Lorrey. “We see through all that with the drone’s LiDAR, using it to strategically target where to take our field samples. Now, we can look at the GPS coordinates of samples we’ve already taken and figure out where the gaps are – where we need to sample next.” Sutton’s three-hour drone flight at Lake Tennyson captured a staggering one billion LiDAR data points, which were processed back at NIWA’s Christchurch lab and turned into a detailed map. This map lets Lorrey and colleagues analyse the old glacial landforms at footprint scale, defining glacier timelines in the landscape and locating boulder samples on them with pinpoint accuracy.
Climate scientist Dr Drew Lorrey takes samples from a boulder left behind by a retreating glacier in North Canterbury’s Tennyson Valley. The boulder was identified using drone-mounted LiDAR. (Rebekah Parsons-King)
Dr Daniel Clements with the aquatic drone – part of NIWA’s suite of high-tech data-gathering tools. (Mary de Winton)
ight hundred kilometres north at NIWA’s Ruakura research facility, freshwater ecologist Dr Daniel Clements and aquatic biology technician Aleki Taumoepeau put a small autonomous boat through its paces in a hydraulic flume pool. At first glance, the sleek aquatic drone looks like the kind of thing that would delight small children. But this is no toy – the technology is integral to developing new techniques for detecting the introduced weeds that plague our lakes and rivers. Invasive aquatic weeds are a major problem in many New Zealand waterways. They outcompete native species, play havoc with our irrigation and hydropower infrastructure, and severely compromise cultural and recreational values. Early detection is the key to e ective control. Working with NIWA’s Instrument Systems and Marine Biosecurity groups, Clements and his team are developing algorithms for a new underwater detection system. Video imagery and hydroacoustic data, captured by sensors as the boat skims over the surface of the water, are combined with an artificial intelligence technology known as ‘deep learning’. This digital advance enables computer software to ‘search’ the video frame by frame for target species – tagging GPS co-ordinates as it goes. The aquatic drone also collects information about bathymetry, sediment and vegetation abundance, resulting in a rapid and cost-e ective detection and mapping tool that can be e ectively used over large areas. The trial is in its early stages, and Clements readily acknowledges that human dive surveys will always play a role in this work. But, drawing parallels with New Zealand’s Covid-19 response, he says the technology o ers huge potential. “Eradicating a freshwater invasive weed by detecting it early is much more feasible and cost-e ective than dealing with a widespread incursion in the long term.”
Aquatic biology technician Aleki Taumoepeau monitors the autonomous drone during weed detection trials on Lake Rototoa near Kaipara. (Daniel Clements)
Dr Leigh Tait
The Boxfi sh ROV reveals the richness of life 70m below in the Ross Sea, including Antarctic scallops, feather and brittle stars, tubeworms and an array of sea cucumbers, corals and urchins. (NIWA)
IWA’s drone capability extends well below the waterline. As well as tracking weeds and sediment fl ows, remote or autonomous vehicles are used, among other things, to assess the health of scallop populations, map ocean currents and measure coastal water quality and algal blooms. Dr Leigh Tait recently broke new ground, dipping under the surface of Antarctica’s icy Ross Sea with a BoxFish ROV (remotely operated vehicle), surveying the Antarctic marine life more than 100 metres below. The vehicle is tethered to a surface ship by cable and “fl own” by Tait using the sensors and high defi nition cameras it carries. Operating out of sight on the Antarctic sea fl oor brings its own set of problems. But high-speed fi bre optic cables have brought a new era of data transfer back to the mother ship, and Tait believes we’re at the start of an explosion of advanced marine ROV use. “We’re now beginning to take what we’ve learnt from using technology on aerial drones and are fi tting out similar, miniaturised systems for underwater use.” Among the rich diversity of Ross Sea life, the recent survey uncovered surprisingly deep and dense stands of large kelp, raising interesting questions about their role in the Antarctic marine carbon cycle. “It really opens up a whole new fi eld of research in how those plants are taking CO2 out of the atmosphere and storing that in the deep cold sea. We really know very little about that.” Tait is already planning how he can get his ROV back down to the Ross Sea to uncover some of the answers. With the advances in technology matched by the relentless march of computer science, expect to see a lot more drone activity in our skies, lakes and distant oceans in the years ahead.
